Global positioning systems “GPS”s enable a user to find their current location. A GPS with a mapping function may store map data that guides a user to their destination. Different types of GPS units exist, including handheld GPS, portable GPS, and built-in GPS. A handheld GPS is are often integrated with a communication device such as a cell phone or a PDA. The handheld GPS may also have Internet access via the cellular or wifi connection in the unit.
GPS units may also include the capability of receiving alternative transmissions. For example, a portable GPS and car mounted GPS may receive supplemental transmissions either via satellite or via some alternative in the end, that includes traffic information. The traffic information, for example, may be transmitted on a low bandwidth channel, in some kind of text format, and maintained within the GPS.